Conventionally, a fluid spring utilizing a pressure of compressive fluid such as air has been used in a suspension device of a vehicle. In the case of using the fluid spring, a vehicle height can be arbitrarily adjusted by the pressure of the compressive fluid, but a stroke sensor for detecting the vehicle height from a stroke of the fluid spring needs to be additionally provided.
JP2002-307925A discloses an air suspension device for vehicle including an air spring arranged between a chassis frame and an axle and a sensor for detecting a stroke of the air spring from an angle of a lever which rotates as a vehicle height changes.